The Gymnic Sit ‘n’ Gym Perla Burst-Resistant Fitness Ball is a modern reinterpretation of the chair. This multi-functional piece of equipment can be used at home, the office or at school to help engage the core while the body is stationary. Manufactured in an elegant pearly white the Gymnic Sit ‘n’ Gym Burst-Resistant Fitness Chair brings fitness into your day-to-day life by encouraging dynamic sitting to help improve balance, coordination, flexibility and stabilization. By incorporating balance-centric exercises in your day enables your muscles to work harder to stabilize your body, thus burning calories. Made from durable, latex-free, vinyl which supports a maximum weight of 270 lbs. and is also phthalate and BPA free. The burst-resistant quality of this exercise ball is possible because of the medical grade resilient material it is made out of. Besides providing high performance and increased safety during use, if the exercise ball is punctured it will deflate slowly, protecting the user from harm. The 55 cm fitness chair is recommended for users 5′ 1″ to 5′ 7″. The 65 cm fitness chair is recommended for users 5′ 8″ to 6′ 2″. The 75 cm fitness chair is recommended for users 6′ 3″ and taller.